Transcranial ultrasound stimulation of the human motor cortex
Yi Zhang, Liyuan Ren, Kai Liu, Shanbao Tong, Ti-Fei Yuan, Junfeng Sun
iScience 2021, 24, 103429 · 10.1016/j.isci.2021.103429
Abstract
It has been 40 years since the report of long-term synaptic plasticity on the rodent brain. Transcranial ultrasound stimulation (TUS) shows advantages in spatial resolution and penetration depth when compared with electrical or magnetic stimulation. The repetitive TUS (rTUS) can induce cortical excitability alteration on animals, and persistent aftereffects were observed. However, the effects of rTUS on synaptic plasticity in humans remain unelucidated. In the current study, we applied a 15-min rTUS protocol to stimulate left primary motor cortex (l-M1) in 24 male healthy participants. The single-pulsed transcranial magnetic stimulation-evoked motor evoked potential and Stop-signal task was applied to measure the rTUS aftereffects. Here, we report that conditioning the human motor cortex using rTUS may produce long-lasting and statistically significant effects on motor cortex excitability as well as motor behavior, without harmful side effects observed. These findings suggest a considerable potential of rTUS in cortical plasticity modulation and clinical intervention for impulsivity-related disorders.
Abstract via europepmc.
Exposures
Exposure 1: rTUS to left primary motor cortex (l-M1)
Target: primary motor cortex — “left primary motor cortex (l-M1)”
Device: Olympus / Panametrics · Olympus NDT · V391-SU ✓
| Waveform | pulsed | |
|---|---|---|
| Fundamental frequency (kHz) | 500 | ✓✓✓ |
| Pulse duration (ms) | not reportedimplied by duty cycle ÷ PRF: 0.5 ms (not stated by the paper) | ⚑ |
| Pulse repetition frequency (Hz) | 100 | ✓✓✓ |
| Duty cycle (%) | 5 | ✓✓✓ |
| Sonication duration (s) | 0.5 | ✓✓✓ |
| Free-field pressure (kPa) | not reported | |
|---|---|---|
| Free-field Isppa (W/cm²) | 8.05 | ✓✓✓ |
| Free-field Ispta (W/cm²) | 0.403 | ✓✓✓ |
| In-situ estimate | simulationsingle value | |
| In-situ pressure (kPa) | not reported | |
| In-situ Isppa (W/cm²) | 2.85 | ✓✓✓ |
| In-situ Ispta (W/cm²) | 0.142 | ✓✓✓ |
| Pressure, domain unspecified (kPa) | 419 | ✓✓✓⚑ |
A 15-minute rTUS session (or sham) was delivered to l-M1 with inter-stimulus interval ISI=8 s and 50 tone-bursts (NTB) per sonication train of 500 ms; total on-state duration of ultrasound across the 15-min session was 2.647-2.657 s. In the sham condition the output of the TUS system was turned off. Sessions (active/sham) were delivered in a crossover design with >7 days washout.
Flags from extraction
exposures[0].timing.pulse_duration_ms— Paper states tone-burst-duration (TBD)=500 ms, identical to the stated sonication duration (SD)=500 ms; duty cycle (5%) divided by PRF (100 Hz) implies an individual burst duration of 0.5 ms, suggesting TBD may be a units typo (500 microseconds). Recorded as stated (500) per the burst rule.exposures[0].unspecified_domain.pressure_kpa— 419 kPa is given as the simulation source/target driving pressure; unclear whether this corresponds to a free-field or in-situ (at-target) domain, so placed in unspecified_domain.auditory_control— No masking sound was used; authors instead selected a transducer/coupler reported to produce no perceivable vibration or sound and had subjects wear earplugs, and argue auditory confound is unlikely; does not map cleanly onto the closed vocabulary.